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This is a laboratory-developed test using analyte specific reagents and research use only reagents. Peripheral blood specimens of chronic lymphocytic leukemia only (but not other hematologic tumor samples) will be analyzed by a screening flow cytometry method to determine B-cell content and confirm the presence of a clonal B-cell population. The B-cell population in blood samples will then be subjected to immunomagnetic bead enrichment (Robosep, Vancouver Canada) and high-quality DNA extracted from the isolated B-cell fraction. DNA is otherwise routinely extracted directly from peripheral blood, bone marrow or fresh/frozen tissue of other specimens without prior enrichment. DNA is amplified by PCR technique targeting exons 4-9 of the TP53 (p53) gene and the PCR product is assessed for adequacy by capillary gel electrophoresis and then subjected to dideoxynucleotide automated Sanger cycle sequencing. Analysis of the sequenced DNA regions is performed using Mutation Surveyor and Alamut software and the sequence data is compared to a reference TP53 gene sequence to identify single nucleotide variants (SNV) or other types of small insertion/deletion nucleobase changes. The presence of a detected mutation is then assessed using a web-based public database of known p53 gene mutations. (http://p53.free.fr/index.html). Results are reported in standard nomenclature according to the most recent Human Genome Variation Society (HGVS) recommendations and an interpretive comment regarding the nature of the mutation (eg, known deleterious, suspected deleterious, synonymous change, etc) will be included to complete the clinical report.(The TP53 Web Site entry UMD TP53 Mutation Database. Available from http://p53.free.fr/index.html Retrieved 12/3/2013; den Dunnen JT, Antonarakis SE: Mutation nomenclature extensions and suggestions to describe complex mutations: a discussion. Hum Mutat 2000;15:7-12)